Building structure, especially air raid shelter

ABSTRACT

A building structure, especially an air raid shelter is formed from prefabricated tubular concrete elements (10) and end wall elements (11), the tubular concrete elements (10) being clamped between the end wall elements (11) with the aid of prestressed prestressing means or ties (12). The tubular concrete elements (10) have at least one stiffening beam (17, 18) extending all around them and at least the interstices between successive stiffening beams are filled with in situ cast concrete (13) reinforced by means of a crossbar (24), which in situ cast concrete encloses the prestressed prestressing means or ties (12). Two or more rows of tubular concrete elements (10) with end wall elements (11) can be placed beside each other to form a large building structure, especially an air raid shelter in which the stiffening beams (17) on the adjoining tubular concrete elements (10) engage each other in a comb-like manner and constitute columns.

This invention relates to a building structure, especially an air raidshelter, comprising a number of adjoining, prefabricated, reinforced,tubular concrete elements and end wall elements clamped together withthe aid of prestressing means. Such air raid shelters are previouslyknown for instance from DE-AS 1,137,545. However, the prior art air raidshelter suffers from great drawbacks inasmuch as it has been producedfrom numerous, relatively small elements and therefore in mounted statehas a great many weakened joints. In order that an air raid shelterproduced from prefabricated elements shall satisfy the high requirementsthat of necessity are nowadays placed on air raid shelters, the air raidshelter must be so constructed that the joints between the prefabricatedelements are tight, that the cohesion between the elements is of such anature that the joints do not imply any weakening compared with an insitu produced or cast air raid shelter structure, and the air raidshelter produced from prefabricated elements must possess a sufficientdeformability, stability and energy absorption to display the samestrength and stability as do in situ produced or cast air raid shelters.The prior art air raid shelter structure disclosed by DE-AS 1,137,545cannot satisfy these requirements. The same applies to other prior artair raid shelters which have wholly or partly been formed byprefabricated elements, such as the air raid shelter according to DE-AS1,052,102. The lack of stability and strength is still more evident inanother prior art type of air raid shelter which has been formed byprefabricated elements, namely the air raid shelter according to DE-AS1,005,260.

The object of the present invention is to provide a building structure,especially an air raid shelter which fulfils the above-mentionedrequirements and, moreover, can be produced from large prefabricatedelements which are readily handled in spite of their size. This andother objects of the invention are realized if the building structure,especially the air raid shelter, is given the characteristic featuresindicated in the appended main claim. In the building structure,especially the air raid shelter according to the invention, the tubularconcrete elements shall thus exteriorly and/or interiorly have at leastone stiffening beam and said stiffening beam shall be formed with holesfor prestressing means or ties to pass through, with the aid of whichmeans or ties the tubular concrete elements are clamped together betweenthe end wall elements. Besides, at least the interstices between thestiffening beams of the adjoining concrete elements shall be filled outwith reinforced in situ cast concrete for permanent interconnection ofthe concrete elements and embedding of the prestressing means or ties soas to provide a structure similar to prestressed concrete.

In a particularly advantageous embodiment of the invention the buildingstructure, especially the air raid shelter, can comprise severaladjoining rooms each of which has a set of delimiting tubular concreteelements. In this case the stiffening beams of the tubular concreteelements of adjoining rooms are offset relative to each other and engagein a comb-like manner with each other. A longitudinal, reinforcedstiffening beam formed of in situ cast concrete is in this case providedat the top and optionally also at the bottom between adjoining sets oftubular concrete elements. In this embodiment of the invention theadjoining rooms of the building structure, especially the air raidshelter, will thus be interconnected via a number of openings defined bycolumns of which each column is thus formed by two adjacent stiffeningbeams of which one stiffening beam belongs to the tubular concreteelements of one room while the other stiffening beam belongs to thetubular concrete elements of the other room.

It is of particular advantage if the stiffening beams of the tubularconcrete elements are placed exteriorly on the top and side faces of theconcrete elements, but placed interiorly at the bottom of the concreteelements. As a result, the underside of the concrete elements can bemade planar and moreover it will be easier to place the concreteelements on a levelled base.

If the building structure, especially the air raid shelter, is formed bysubstantially square or rectangular tubular concrete elements it isrecommended to place the prestressing means or ties in the region of thecorners of the concrete elements. If need be, the prestressing means orties may however be placed also between the corner portions.

The individual tubular concrete elements are so dimensioned that eachelement can withstand the loads determinative of the dimensions of thebuilding construction or air raid shelter. The finished building or airraid shelter structure which thus comprises the prefabricated concreteelements and reinforced in situ cast concrete, can take up very largestresses because the joining together of the individual elements will bevery effective by reason of the reinforced in situ cast concrete andbecause the reinforcement of the in situ cast concrete serves as astress-distributing crossbar and makes it possible to space thestiffening beams a large distance apart without resulting in anunpermissible weakening of the structure.

In an embodiment of the invention, the reinforcement of the in situ castconcrete may have its longitudinal reinforcing means passed throughthrough-holes in the stiffening beams of the tubular concrete elements,but in another embodiment of the invention, the reinforcement may alsohave been placed outside the stiffening beams in an in situ castconcrete layer which encloses them. In the latter case the stiffeningbeams on the outer side of the tubular concrete elements may preferablyhave protruding lugs for the fixation of forms for the in situ castingof concrete.

As mentioned in the foregoing it is essential that the cohesion betweenthe prefabricated concrete elements is such that joints do not imply anyweakening compared with an in situ produced building or air raid shelterstructure. To be sure that such a cohesion is realized it isrecommended, in a particularly advantageous embodiment of the invention,to provide the end surfaces of the tubular concrete elements with twodefining flanges which protrude differently far and define an annulargroove. On in situ cast concreting, said groove is then filled with insitu cast concrete which is preferably reinforced so that saidpreferably reinforced in situ cast concrete forms a locking tongue. Torealize this the defining flange closest to the stiffening beam of theconcrete elements shall be the shortest, while the adjoining concreteelement should have its longer defining flanges placed close to eachother. Moreover, the peripheral edge of the end wall elements should beenclosed by reinforced in situ cast concrete at least within the areaswhere the prestressing means are anchored in the end wall elements.

The invention will be more fully described below in connection with airraid shelters and with reference to some embodiments illustrated in theaccompanying drawings in which:

FIG. 1 is a diagrammatic sketch showing a perspective view of anembodiment of an air raid shelter according to the invention;

FIG. 2 is a section on line II--II in FIG. 1 after the air raid shelterhas been finished;

FIG. 3 is a diagrammatic horizontal section of a second embodiment of anair raid shelter according to the invention;

FIG. 4 is a vertical section on line IV--IV in FIG. 3;

FIG. 5 partly in section and partly in plan view shows a tubularbuilding element of the air raid shelter;

FIG. 6 is a section on line VI--VI in FIG. 5;

FIG. 7 is a section on line VII--VII in FIG. 4;

FIG. 8 is a section on line VIII--VIII in FIG. 4;

FIG. 9 is a section on line IX--IX in FIG. 3;

FIG. 10 is a partial side view on line X--X in FIG. 3;

FIG. 11 shows a further embodiment of an air raid shelter according tothe present invention;

FIG. 12 is a section on line XII--XII in FIG. 11 after the in situconcreting operation;

FIG. 13 is a plan view of the area XIII in FIG. 11 before the in situconcreting operation; and

FIG. 14 is a section on line XIV--XIV in FIG. 13.

As will appear from FIGS. 1 and 2, an air raid shelter according to thepresent invention can be in the form of a detached building which mayserve in peace time for instance as a garage. Alternatively, the airraid shelter may be a store-room of a building or be parts of a basementof a building, say a detached house or apartment building.

As will appear from FIGS. 1 and 2, an air raid shelter according to theinvention is constructed from a number of tubular, reinforced concreteelements 10 and end wall elements 11 at the ends of the row of tubularconcrete elements. The tubular concrete elements 10 are clamped betweenthe end wall elements 11 with the aid of a number of prestressing meansor ties 12, in the present instance four such prestressing means at eachcorner. The prefabricated concrete elements which may have a length ofabout 2.5 m, a width of about 4.5 m and a height of about 2.6 m and mayweigh 10 to 12 tons, are besides united by means of reinforced in situcast concrete 13. Said in situ cast concrete 13 is cast between theconcrete elements 10, 11 and exteriorly fastened plate forms 14. In theillustrated embodiment the garage building or air raid shelter buildinghas been supplemented with a heat insulation 15 and a facing 16 on thewalls and the roof. The stationary air raid shelter equipment 38 ispreferably concreted in an end wall element 11.

According to the invention, the tubular concrete elements have astiffening beam which extends all around them and which in theembodiment illustrated has its parts 17 placed on the outer side of thetubular concrete elements, while the part 18 of the stiffening beam isplaced on the inner side of the concrete element. This will be seen fromFIGS. 1 and 2, where FIG. 1 in its left-hand portion shows the elementsbefore the in situ concreting of the concrete layer 13 and a floorconcrete layer.

As more closely described in conjunction with the embodiment accordingto FIGS. 3-10 the tubular concrete elements 10 and the end wall elements11 are provided with holes 19 for the prestressing means or ties 12 topass through. As a result, the concrete elements 10 can be clampedbetween the end wall elements 11. At the in situ concreting of theconcrete layers 13 the prestressing means 12 will be wholly enclosed byconcrete and will remain therein as a type of prestressing steel, evenif said prestressing steel should not be included in the calculations ofstrength of the structure. As already mentioned the in situ castconcrete also has a reinforcement 24 which is only hinted at in FIGS. 1and 2, but which serves as a crossbar which shall distribute thestresses at the joints between the individual concrete elements anddistribute them in the longitudinal direction of the elements so thatthe joints will not imply any impermissible weakening of the air raidshelter structure.

The embodiment of the invention illustrated in FIGS. 3-10 differs fromthat in FIG. 1 mainly in view of the positioning of the crossbar in thestructure. In the embodiment according to FIGS. 1 and 2, the crossbar 24is placed between the stiffening beams 17, 18 although part of saidcrossbar may have been passed through holes in said stiffening beams. Inthe embodiment according to FIGS. 3-10 the major part of the crossbar 24has been passed outside of the stiffening beams 17 on the two side wallsof the air raid shelter and in the roof thereof, the major part of thestiffening beams being enclosed in an in situ cast concrete layer 13which is of the requisite thickness to embed the crossbar.

FIG. 3 shows a horizontal section of three concrete elements 10 whichhave been placed after one another on a levelled base 36 (FIG. 4) andwhich differ from the concrete elements 10 in FIGS. 1 and 2 only inregard of the existence of protruding fastening lugs 20.

In addition to the holes 19, the concrete elements 10 are provided witha number of holes 21 (FIG. 4) through which pass some reinforcement bars27 of a non-tensioned reinforcement 24-27 which is more fully describedin the following. AT the corners the concrete elements have beenstrengthened by means of fillets 22. As will appear from the section inthe left-hand portion of FIG. 4 and from the section in FIG. 6 there isa strong reinforcement in the wall portions 23 and the stiffening beams17, 18.

In FIGS. 4-6 the in situ cast concrete has been wholly omitted, whilethe outer defining line of the in situ cast concrete has been marked bydash and dot lines in FIGS. 3 and 7-9.

FIG. 7 which is a horizontal section on line VII--VII in FIG. 4, showshow the crossbar 24-27 has been placed and anchored in the walls of theair raid shelter. It thus appears from the Figure that said crossbar hasa welded mesh reinforcement 24 which extends around the corners andemerges at the outside of the end wall elements 11 passing between thelugs 20 of the stiffening beams 17. The crossbar also comprises stirrups25, 26 which protrude into the joint areas between adjoining concreteelements 10, 11. Besides, the crossbar comprises reinforcement bars 27which have been passed through the holes 21 and anchored at their endsin the end wall elements 11.

The anchorage of the prestressing means in the air raid shelterstructure is shown in detail in FIG. 8. It thus appears from this Figurethat the prestressing means 12 extend through the holes 19 and have beenanchored by means of washer and nut 28 on the outer side of the end wallelements 11. The same fastening method has been exploited to anchor theprestressing ties 12 which are provided in the floor and extend throughthe stiffening beams 18 (see FIG. 9).

In a particularly advantageous embodiment of the invention the tubularconcrete elements have been formed in their end surfaces with twodefining flanges 29, 30 which protrude differently far so as to definein said end surfaces an annular groove 31. The flange 29 located on thesame side of the concrete element as the stiffening beam 17, 18 isshorter than the other flange 30 so that the two facing grooves ofadjoining concrete elements can be filled with in situ cast concrete toform a locking tongue which aids in preventing a lateral displacement ofthe concrete elements in relation to each other. A washer 37 may beplaced in the corner areas of the concrete elements.

It will be seen from FIGS. 3-10 that the finished air raid shelter willhave a very great structural strength because of the stiffening beams17, 18 and the crossbar 24-27 in the in situ cast concrete. To improvethe bond between the prefabricated elements and the in situ castconcrete the surfaces of the prefabricated elements to be connectedtogether may have been given a certain roughness. As the in situ castconcrete extends around the edge portions of the end wall elements atleast in the region of the prestressing means or ties 12, there isobtained a particularly good structural strength in the corner portions.

A special and advantageous embodiment of the invention is shown in FIGS.11-14. This embodiment is intended especially for large air raidshelters where the span would otherwise become too large to permit theprefabricated concrete elements to be handled in an acceptable manner.In the embodiment according to FIGS. 11-14 two sets of tubular elements10 have thus been placed beside one another and interconnected. Thesetubular elements 10 differ from the tubular elements according to theembodiments earlier described in that parts of the wall portions 23 inthe facing walls of the two sets have been omitted, while retaining onlythe stiffening beam portions 17. This will be clearly seen from FIG. 11which shows a horizontal section of the prefabricated concrete elementsof the air raid shelter before the in situ concreting and before thesupply of the requisite reinforcement and prestressing ties. It thusappears from the Figure that the stiffening beams 17 on the two rows ofconcrete elements engage each other in a comb-like manner underformation of columns and leaving through-openings 32 at certain points.

The two rows of concrete elements 10 are clamped between the end wallelements 11 in the same way as in the embodiments earlier described.However, two of the prestressing ties 12 in the wall portion common tothe two rows have been omitted for lack of space. However, they canstill be utilized but in such a case one has to accept a thresholdbetween the two air raid shelter portions.

FIG. 12 which is a section on line XII--XII in FIG. 11, illustrates thereinforcement of the in situ cast concrete and shows the air raidshelter after said in situ concreting operation. It thus appears fromthe Figure that some of the prestressing ties 12 are utilized as areinforcement in longitudinal beams in the roof and floor in the areabetween the two air raid shelter columns. It further appears that thecrossbar 24-27 extends over both air raid shelter portions. If desired,use may optionally be made of the thickened portion 33 shown by dashlines, which in such a case may have a longitudinal reinforcement 34which together with the prestressing ties 12 forms a reinforcement inthe resulting longitudinal beam.

FIGS. 13 and 14 show details of this embodiment and illustrate how thetwo adjoining end elements for the sets of tubular concrete elements canbe interconnected with the reinforcement 35 and the in situ castconcrete 13. FIG. 14 in more detail shows how the joint region betweenthe prefabricated tubular concrete elements of the two adjoining airraid shelter portions is arranged.

We claim:
 1. An air raid shelter comprising a number of adjoining,prefabricated, reinforced, tubular concrete elements (10) and end wallelements (11) clamped together with the aid of prestressing means (12),wherein each of the tubular concrete elements (10) has at least oneexteriorly, interiorly or both exteriorly and interiorly protruding,reinforced stiffening beam (17, 18) integral with the remaining concreteelement and having holes (19) formed in the axial direction of thetubular concrete elements for the prestressing means (12) to passthrough, which prestressing means are anchored to the end wall elementsand serve to clamp together the tubular concrete elements (10) betweenthe end wall elements (11), and wherein interstices are formed betweenthe stiffening beams (17, 18) of adjoining concrete elements (10, 11)and said interstices are filled with reinforced in situ cast concrete(13) for permanent interconnection of the concrete elements (10, 11) andembedding of the prestressing means (12) so as to form prestressedconcrete.
 2. An air raid shelter as claimed in claim 1, in which thetubular concrete elements (10) are of substantially square orrectangular cross-section, and wherein the prestressing means (12) arearranged in the region of the corners of the concrete elements (10). 3.An air raid shelter as claimed in claim 1 or 2, wherein the tubularconcrete elements (10) in their end surfaces have two defining flanges(29, 30) which protrude differently far and define an annular groove(31), the defining flange (29) closest to the stiffening beam (17, 18)of the concrete element being the shortest, while the adjoining concreteelement has its longer defining flanges (30) placed close to each otherin order to permit, on in situ concreting, introduction of concrete andreinforcement (25, 26) to form a locking tongue.
 4. An air raid shelteras claimed in claim 3, wherein the stiffening beams (17) on the outerside of the concrete elements (10) having protruding lugs (20) for thefastening of forms for in situ concreting.
 5. An air raid shelter asclaimed in claim 3, wherein the peripheral edges of the end wallelements (11) are enclosed by reinforced in situ cast concrete (13) atleast in the regions where the prestressing means (12) are anchored inthe end wall elements.
 6. An air raid shelter as claimed in claim 3,wherein the stiffening beams (17, 18) are also provided with holes (21),formed in the axial direction of the concrete elements (10, 11) topermit passing through said holes through reinforcing elements (27) of anon-tensioned reinforcement (24-27) for the in situ cast concrete (13).7. An air raid shelter as claimed in claim 3, wherein the structurecomprises several adjoining rooms each of which has a set of delimitingtubular concrete elements (10), the stiffening beams (17) on the tubularconcrete elements of adjoining rooms being offset in relation to eachother and engaging each other in a comb-like manner, and a longitudinal,reinforced stiffening beam of in situ cast concrete being formed at thetop and optionally also at the bottom between adjoining sets of tubularconcrete elements.
 8. An air raid shelter as claimed in claim 3, whereinthe tubular concrete elements (10) have internal strengthening means(22) in their corner regions.
 9. An air raid shelter as claimed in claim3, wherein the stiffening beams (17, 18) are arranged exteriorly at thetop and at the sides of the tubular concrete elements (10) and arearranged interiorly at the bottom of the tubular concrete elements (10).10. An air raid shelter as claimed in claim 3, wherein the air raidshelter contains stationary air raid shelter equipment and the equipmentis arranged on and united with the end wall elements (11).
 11. Abuilding structure comprising a number of adjoining, prefabricated,reinforced tubular concrete elements and end wall elements clampedtogether with the aid of prestressing means,wherein each of the tubularconcrete elements is of substantially square or rectangularcross-section and each of the tubular concrete elements has at least oneexteriorly, interiorly or both exteriorly and interiorly protruding,reinforced stiffening beam integral with the remaining concrete elementand having holes formed in the axial direction of the tubular concreteelements for the prestressing means to pass through, which prestressingmeans are arranged in the region of the corners of the concrete elementsand are anchored to the end wall elements and serve to clamp togetherthe tubular concrete elements between the end wall elements, and whereininterstices are formed between the stiffening beams of the joiningconcrete elements and said interstices are filled with reinforced insitu cast concrete for permanent interconnection of the concreteelements and embedding of the prestressing means so as to formprestressed concrete, and wherein the stiffening beams on the outer sideof the concrete elements have protruding lugs for the fastening of formsfor in situ concreting.
 12. A building structure as claimed in claim 11wherein the peripheral edges of the end wall elements are enclosed byreinforced in situ cast concrete at least in the regions whereprestressing means are anchored in the end wall elements.
 13. A buildingstructure as claimed in claim 11 wherein the stiffening beams are alsoprovided with holes formed in the axial direction of the concreteelements to permit passing through said holes through reinforcingelements of a non-tensioned reinforcement for the in situ cast concrete.14. A building structure as claimed in claim 11 wherein the structurecomprises several adjoining rooms each of which has a set of delimitingtubular concrete elements, the stiffening beams on the tubular concreteelements of adjoining rooms being offset in relation to each other andengaging each other in a comb-like manner, and a longitudinal,reinforced stiffening beam of in situ cast concrete being formed at thetop and optionally also at the bottom between adjoining sets of tubularconcrete elements.
 15. A building structure as claimed in claim 11wherein the tubular concrete elements have internal strengthening meansin their corner regions.
 16. A building structure as claimed in claim 11wherein the stiffening beams are arranged exteriorly at the top and atthe sides of the tubular concrete elements and are arranged interiorlyat the bottom of the tubular concrete elements.